Washing machine and control method thereof

ABSTRACT

Disclosed herein are a washing machine having a plurality of washtubs and a control method thereof. In the washing machine having a plurality of washtubs, if it is determined that a washtub that is not in operation is present, dozens of liters of water used in a washtub that is in operation are moved into and stored in the non-operating washtub rather than being discharged to the outside. The moved water may be utilized in a following washing or rinsing stage of the washtub, or a washing or rinsing stage of the other washtub.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Korean Application No.10-2009-41234, filed May 12, 2009, in the Korean Intellectual PropertyOffice, the disclosure of which is incorporated herein by reference.

BACKGROUND

1. Field

This application generally relates to a washing machine that is capableof recycling rinse water.

2. Description of the Related Art

Generally, a washing machine (i.e. a conventional drum washing machine)includes a single washtub, in which dirty laundry is washed using waterand detergent. To wash laundry, the washing machine performs a series ofoperations, such as a washing stage, rinsing stage, dehydrating stage,etc.

With respect to laundry washing, it may often be impossible to wash alllaundry in a single washtub due to differences in the type or qualitythereof. Thus, in the case of a washing machine having a single washtub,a user may need to sort different clothing that is difficult to washtogether, to wash the clothing separately. This causes inconvenience dueto separate washing and forces the user to operate the washing machineseveral times (e.g., two times), resulting in a serious waste of timeand energy. In addition, if a large-capacity washtub is used to washonly a small quantity of laundry, operating the large-capacity washtubcauses unnecessary power consumption.

The entire washing operation of a washing machine is divided into awashing stage, rinsing stage, and dehydrating stage, and causesconsumption of considerable water because wash water used in the risingstage is directly discharged to the outside rather than being recycled.Moreover, the rinsing stage may be carried out at least three times andin the extreme case, five or six times based on the quantity of laundryor the user's selection, causing an increase in the consumption ofwater. In particular, disposing water used in the last one of severalrinsing strokes without recycling despite the water being relativelyclean may problematically increase the usage of water in a washingmachine.

Recently, a drying function has been added to a washing machine,allowing the washing machine to perform even a drying stroke in whichdehydrated laundry is dried. The washing machine having the dryingfunction includes a drying device, which blows hot air generated by adrying heater into a space, in which laundry is received, so as to drythe laundry. This kind of washing machine may perform the dryingfunction independently using the drying device, or may perform thedrying function after completion of a dehydrating stage in associationwith a washing function.

If the drying stroke begins, a blowing fan is operated and the dryingheater is turned on, causing hot air from the drying heater to be blowninto a rotating tub in which laundry is received. Thereby, the laundryin the rotating tub is dried as the laundry repeatedly rises and fallsdue to rotation of the tub. The high-temperature air blown into therotating tub is changed into wet vapor containing moisture absorbed fromthe laundry, and the resulting wet vapor is directed along a wallsurface of a washtub toward the blowing fan. In this case, as cold wateris ejected from a condensing hose connected to an external water sourceto the wall surface of the washtub, the moisture contained in the wetvapor to be suctioned to the blowing fan after being circulated in therotating tub is condensed on the wall surface of the washtub and movesdown. A small quantity of condensed water collected at the bottom of therotating tub is discharged to the outside through a discharge hole.

Drying laundry as described above may require supply of water from anexternal source, and the supplied water is directly disposed of withoutrecycling despite the water being relatively clean, resulting inincrease in the usage of water in a washing machine.

SUMMARY

Therefore, it is an aspect of the present invention to provide a washingmachine having a plurality of washtubs and a control method thereof,which may reduce the quantity of water used in the washing machine tothe maximum extent.

Additional aspects of the invention will be set forth in part in thedescription which follows and, in part, will be apparent from thedescription, or may be learned by practice of the invention.

The foregoing and/or other aspects of the present invention are achievedby providing a control method of a washing machine having a plurality ofwashtubs, the method including determining whether or not a washtub thatis in operation is present, and if the presence of the washtub that isin operation is determined, moving water used in the washtub that is inoperation to a washtub that is not in operation.

The determination of the presence of the washtub that is in operationmay include determining whether or not a washtub that is performing anyone of a washing stage, rinsing stage, dehydrating stage, and dryingstage is present.

The determination of the presence of the washtub that is in operationmay include determining whether or not a washtub that is in a lastrinsing stage is present.

The determination of the presence of the washtub that is in operationmay include determining whether or not a washtub that is in the dryingstage is present.

The control method may further include sensing the level of watergenerated in the drying stage of the washtub that is in operation, andmoving the water generated in the drying stage to the washtub that isnot in operation if the sensed level of water is a preset value or more.

The control method may further include storing the water moved into thewashtub that is not in operation until the washtub that is in operationis stopped.

The water, moved into the washtub that is not in operation, may bereturned when the washtub that is in operation performs any one of afollowing washing stroke and rinsing stroke.

The foregoing and/or other aspects of the present invention are achievedby providing a control method of a washing machine having a plurality ofwashtubs, the method including determining whether or not a washtub thatis in operation is present, if the presence of the washtub that is inoperation is determined, determining whether or not movement of waterused in the operation is needed, and if movement of the water used inthe operation is needed, moving the water used in the operation to awashtub that is not in operation.

The determination as to whether movement of the water used in theoperation is needed may include determining whether or not the washtubthat is in operation completes a last rinsing stage, and determiningwhether or not the level of water generated in a drying stage reaches apreset value.

The foregoing and/or other aspects of the present invention are achievedby providing a washing machine including a plurality of washtubsincluding a washtub that is in operation and an additional washtub, awater moving device to move water between the plurality of washtubs, anda controller to control the water moving device to move the water usedin a washtub that is in operation to an additional washtub.

The controller may move water used in a washtub that is in a lastrinsing stage or in a drying stage into a washtub that is not inoperation.

The controller may move water used in a washtub that is performing anyone of a washing stage, rinsing stage, dehydrating stage, and dryingstage to a washtub that is not in operation.

The water moved into the additional washtub may be stored under controlof the controller until the washtub that is in operation is stopped.

The controller may return the water moved into the additional washtubwhen the washtub that is in operation performs any one of a followingwashing stage and rinsing stage.

The water moving device may include at least one connecting pipeconnecting two washtubs to each other, and an opening/closing valve andpump provided at the connecting pipe.

The connecting pipe may have one end connected to at least one of adrainpipe and condensing duct of a first washtub, and the other endconnected to at least one of a drainpipe and condensing duct of a secondwashtub.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects of the invention will become apparent andmore readily appreciated from the following description of theembodiments, taken in conjunction with the accompanying drawings ofwhich:

FIG. 1 is a perspective view illustrating an external appearance of awashing machine according to an exemplary embodiment of the presentinvention;

FIG. 2 is a sectional view illustrating an interior configuration of thewashing machine according to the embodiment of FIG. 1;

FIG. 3 is a schematic control block diagram of the washing machineaccording to the embodiment of FIG. 1;

FIG. 4 is a flow chart illustrating a control operation of the washingmachine according to the embodiment of FIG. 1;

FIG. 5 is a view illustrating movement of rinse water used in the lastrinsing stroke in the case where a first washtub is not in operation anda second washtub is in the last rinsing stroke in the washing machineaccording to the embodiment of FIG. 1;

FIG. 6 is a view illustrating a state wherein the rinse water used inthe last rinsing stroke is stored in the second washtub in the washingmachine according to the embodiment of FIG. 1;

FIG. 7 is a flow chart illustrating a control operation of a washingmachine according to a second embodiment of the present invention;

FIG. 8 is a view illustrating movement of water generated in a dryingstroke in the case where the first washtub is not in operation and thesecond washtub is in the drying stroke in the washing machine accordingto the second embodiment of the present invention;

FIG. 9 is a view illustrating a state wherein the water generated in thedrying stroke is stored in the second washtub in the washing machineaccording to the second embodiment of the present invention; and

FIG. 10 is a flow chart illustrating an operation of moving water storedin one washtub into the other washtub to be newly operated in a washingmachine according to a third embodiment of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS

Reference will now be made in detail to the embodiments, examples ofwhich are illustrated in the accompanying drawings, wherein likereference numerals refer to the like elements throughout. Theembodiments are described below to explain the present invention byreferring to the figures.

FIG. 1 illustrates an external appearance of a washing machine accordingto an exemplary embodiment of the present invention.

As shown in FIG. 1, the washing machine according to the embodiment ofthe present invention includes a body 10 defining an external appearanceof the washing machine, and a plurality of doors (e.g. two doors) 11 and12 provided at upper and lower parts of the body 10 for input oflaundry. An input unit 400 to allow a user to input commands related towashing courses and operations of the washing machine and a display unit410 to display the washing courses and operations of the washing machineare arranged between the plurality of doors 11 and 12.

The input unit 400 includes a power button, an operating/stoppage buttonto begin an operation of the washing machine, a washtub selecting buttonto allow the user to perform, e.g., simultaneous washing/dryingoperations or independent washing/drying operations using at least aselected one of a plurality of washtubs (e.g. two washtubs) that areprovided to enable sorted washing of laundry, and other course andfunction buttons used to select a washing course and washing function ofeach washtub. Of course, the form of the input unit 400 is not limitedto that shown, and various other forms may also be possible.

Detergent supply units 21 and 22 to supply detergent into the pluralityof washtubs are provided respectively at the left upper end and centerof the body 10.

Although the embodiment of FIG. 1 illustrates the detergent supply units21 and 22 to supply detergent into the plurality of washtubs,respectively, it may also be possible to realize a single detergentsupply unit 21 or 22, a detergent flow path of which is divided intoseveral paths connected to the plurality of washtubs, to supplydetergent into the respective washtubs. In addition, positions of thedetergent supply units 21 and 22 are not limited thereto, and thedetergent supply units 21 and 22 may be installed at any other positionswhere the user may easily input detergent.

FIG. 2 illustrates an interior configuration of the washing machineaccording to the embodiment of the present invention of FIG. 1.

As shown in FIG. 2, in the washing machine according to the embodimentof FIG. 1, the plurality of washtubs (e.g., two washtubs) is verticallydivided to enable sorted washing of laundry based on the capacity ortype of the laundry. For example, a first washtub 31 for large-capacitywashing (e.g., 13 Kg) is provided as a lower washtub, and a secondwashtub 32 for small-capacity washing (e.g. 3 Kg) is provided as anupper washtub.

Although the first and second washtubs 31 and 32 may have the samecapacity range as occasion demands, differentiating the large-capacityand small-capacity washtubs may be more advantageous in consideration ofcharacteristics of the washing machine having the plurality of washtubs31 and 32. This serves, as mentioned above, to prevent unnecessary powerwaste by operating only the small-capacity second washtub 32 in the caseof washing of a small quantity of laundry.

The first and second washtubs 31 and 32 have the same basicconfiguration, and cylindrical first and second drums 41 and 42perforated with a plurality of holes are rotatably installedrespectively in the first and second washtubs 31 and 32. Also, first andsecond motors 61 and 62 are mounted to rear outer surfaces of the firstand second washtubs 31 and 32 and serve as drive devices to rotate firstand second rotating shafts 51 and 52 connected to the first and seconddrums 41 and 42, so as to perform washing, rinsing, and dehydratingstages. Of course, the first and second motors 61 and 62 are not limitedto the illustrated example, and the respective washtubs may be operatedsimultaneously or independently using a single motor, drive belt,clutch, etc.

First and second washing heaters 71 and 72 to heat water in the firstand second washtubs 31 and 32 are installed respectively in the bottomregions of the first and second washtubs 31 and 32. Also, first andsecond water supply devices 101 and 102 are installed above the firstand second washtubs 31 and 32, to supply water (wash water or rinsewater) into the respective washtubs. The first and second water supplydevices 101 and 102 include first and second water supply pipes 121 and122, which connect an external water supply pipe 110 to the first andsecond detergent supply units 21 and 22 so as to supply water (washwater or rinse water) into the first and second washtubs 31 and 32, andfirst and second water supply valves 131 and 132 installed on positionsof the first and second water supply pipes 121 and 122 to control watersupply. With this configuration, water to be supplied into the first andsecond washtubs 31 and 32 moves by way of the first and second detergentsupply units 21 and 22, thereby being supplied into the first and secondwashtubs 31 and 32 together with detergent in the first and seconddetergent supply units 21 and 22.

In the embodiment of the present invention, additionally, first andsecond drying devices 201 and 202 are installed to dry laundry in thefirst and second washtubs 31 and 32. The first and second drying devices201 and 202 include first and second drying ducts 211 and 212, which areinstalled on the first and second washtub 31 and 32 and are used tointroduce hot air into the first and second washtubs 31 and 32, firstand second condensing ducts 221 and 222, which are installed at the rearside of the first and second washtubs 31 and 32 and are used to removewet vapor generated in a drying stroke, first and second drying heaters231 and 232 and first and second drying fans 241 and 242, which areinstalled in the first and second drying ducts 211 and 212 and are usedto supply the hot air, and condensers installed in the first and secondcondensing ducts 221 and 222. The condensers include first and secondejecting nozzles 281 and 282, which are installed in the first andsecond condensing ducts 221 and 222 and are used to eject cold water,first and second cold water supply hoses 251 and 252 to supply coldwater into the first and second ejecting nozzles 281 and 282, and firstand second cold water valves 261 and 262, which are installed onpositions of the first and second cold water supply hoses 251 and 252and are adapted to be opened or closed for supply of cold water. Thefirst and second condensing ducts 221 and 222 have discharge holesformed in the bottoms thereof for discharge of condensed water, andfirst and second drainpipes 311 and 312 are connected to the dischargeholes via first and second drain hoses 271 and 272.

With the above-described configuration, air blown by operation of thefirst and second drying fans 241 and 242 is supplied into the first andsecond washtubs 31 and 32 after being heated by the first and seconddrying heaters 231 and 232, thereby acting to heat and dry laundry inthe washtubs. Then, moisture contained in wet vapor generated in thedrying of laundry may be removed while the wet vapor is suctioned to thefirst and second drying fans 241 and 242 through the first and secondcondensing ducts 221 and 222.

The first and second condensing ducts 221 and 222 define flow-pathsextending between first and second air outlets 291 and 292 formed nearthe rear bottoms of the first and second washtubs 31 and 32 and suctionports of the first and second drying fans 241 and 242 installed on thefirst and second washtubs 31 and 32. The first and second condensingducts 211 and 222 are bent by a predetermined curvature, an open side ofeach of which comes into direct contact with the rear surface of thefirst or second washtub 31 or 32 and the suction port of the first orsecond drying fan 241 or 242. Accordingly, the first and second dryingfans 241 and 242 are operated to circulate air in, e.g., the dryingstroke through the first and second air outlets 291 and 292 of the firstand second washtubs 31 and 32, first and second condensing ducts 221 and222, first and second drying fans 241 and 242, first and second dryingducts 211 and 212, and air inlets of the first and second washtubs 31and 32 in sequence. The water supplied into the first and secondcondensing ducts 221 and 222 moves through the first and secondcondensing ducts 221 and 222 and is collected in the first and secondwashtubs 31 and 32. The collected water is periodically pumped so as tobe drained to the outside by first and second drain devices 301 and 302that will be described hereinafter, or is moved into and stored in thefirst or second wash tub (i.e. a washtub that is not in operation) by awater moving device 500 that will be described hereinafter. Here, thenon-operating washtub denotes a washtub not actively under control, suchas, e.g., a washtub stopped in operation or washtub before a washingstroke. Although details will be given hereinafter, the reason formoving water into the non-operating washtub is that the non-operatingwashtub has fewer control obstructing factors, such as, e.g., wetting oflaundry and increase in the supply quantity of water. Reference numerals81 and 82 represent first and second water-level sensors, which serve tosense the level of water generated in the drying stage.

Although this embodiment of the present invention employs the first andsecond drying devices 201 and 202 to dry laundry in the respective firstand second washtubs 31 and 32, the drying device 211 or 212 may bemounted to only one of the first and second washtubs 31 and 32 based onthe design of the washing machine. For example, the first drying device201 may be mounted to only the first washtub 31. In this case, a pump503 may be omitted. Alternatively, the second drying device 202 may bemounted to only the second washtub 32.

In this embodiment of the present invention, the first and second draindevices 301 and 302 are installed to drain water received in the firstand second washtubs 31 and 32. The first and second drain devices 301and 302 include the first and second drainpipes 311 and 312 connected tothe bottoms of the first and second washtubs 31 and 32 so as to guidethe water to the outside, and first and second drain pumps 321 and 322installed on the first and second drainpipes 311 and 312. Each of thefirst and second drain devices 301 and 302 communicates with an externaldrainpipe 330.

Although this embodiment of the present invention employs the first andsecond drain pumps 321 and 322 to drain water from the first and secondwashtubs 31 and 32, the upper washtub of the washing machine, i.e. thesecond washtub 32 may be provided with a drain valve based on theconfiguration of the washing machine, allowing water in the secondwashtub 32 to be drained according to gravity.

In the embodiment of the present invention, the water moving device 500is provided to move water from an operating washtub to a non-operatingwashtub, for example, to move water from the first washtub 31 to thesecond washtub 32, or vice versa. In this case, the water generated inthe drying operation includes water supplied from an external watersource, and condensed water obtained as moisture contained in airdischarged from the washtub is condensed by the supplied water. Thewater moving device 500 includes a connecting pipe 501 to connect thefirst drainpipe 311 of the first washtub 31 to the second drainpipe 312of the second washtub 32, and an opening/closing valve 502 and the pump503 installed on the connecting pipe 501. The connecting pipe 501connects a front end of the first drain pump 321 on the first drainpipe311 of the first washtub 31 to a front end of the second drain pump 322on the second drainpipe 312 of the second washtub 32. In this case, theconnecting pipe 501 may connect the first condensing duct 211 of thefirst washtub 31 to the second condensing duct 222 of the second washtub32 by connecting the first drain hose 271 and second drain hose 272 toeach other.

One end of the connecting pipe 501 may be connected to any one or bothof the first drainpipe 311 and first condensing duct 221, and the otherend of the connecting pipe 501 may be connected to any one or both ofthe second drainpipe 312 and second condensing duct 222. That is, theconnecting pipe 501 may connect a drainpipe of an operating washtub to adrainpipe of a non-operating washtub, a condensing duct of the operatingwashtub to the drainpipe of the non-operating washtub, the drainpipe ofthe operating washtub to a condensing duct of the non-operating washtub,or the condensing duct of the operating washtub to the condensing ductof the non-operating washtub.

The connecting pipe 501 is provided with the opening/closing valve 502and pump 503. For example, the opening/closing valve 502 may be locatednear a junction of the connecting pipe 501 and second drainpipe 312. Inthis case, when it is unnecessary to direct water from the first washtub31 to the second washtub 32 through the connecting pipe 501, it may bepossible to reduce the quantity of water filled in a region of theconnecting pipe 501 communicating with the first drainpipe 311. Also,the pump 503 may be located near a junction of the connecting pipe 501and first drainpipe 311. In this case, when it is necessary to directwater from the second washtub 32 to the first washtub 31 through theconnecting pipe 501, enhanced pumping efficiency may be accomplished.The enhanced pumping efficiency may also be accomplished even when it isnecessary to direct water from the second washtub 32 to the firstwashtub 31 later.

FIG. 3 illustrates a schematic control configuration of the washingmachine according to the embodiment of the present invention of FIG. 1.

As shown in FIG. 3, the washing machine according to this embodiment ofthe present invention includes the input unit 400, a controller 402, anda drive unit 404.

The input unit 400 is used to input operational information, related towashing courses and washing functions (e.g., simultaneous washing/dryingor independent washing/drying) of the first and second washtubs 31 and32 that are selected to be simultaneously or independently used, intothe controller 402. The controller 402 controls respective devices ofthe washing machine in response to commands input by the user via theinput unit 400. For example, to perform washing/dehydrating/dryingstrokes, the controller 402 may control devices for thewashing/dehydrating/drying strokes, i.e. the first and second motors 61and 62, first and second washing heaters 71 and 72, first and secondwater supply valves 131 and 132, first and second drying heaters 231 and232, first and second drying fans 241 and 242, first and second coldwater valves 261 and 262, first and second drain pumps 321 and 322,opening/closing valve 502, and pump 503. In a control method as will bedescribed hereinafter, the controller 402 determines the operatingstages of the first and second washtubs 31 and 32 and also, determineswhether or not the respective devices are in operation.

The first and second water-level sensors 81 and 82 are installed closeto the first and second air outlets 291 and 292 that are formed near therear bottoms of the first and second washtubs 31 and 32 and serve tosense the level of water generated in the drying stage.

The controller 402 determines whether or not the first washtub 31 andsecond washtub 32 are in operation. If any one washtub is in operationand the other washtub is not in operation, the controller 402 moveswater used in the operation, e.g., moves water from the operatingwashtub into the non-operating washtub, allowing the water to be storedin the non-operating washtub. More particularly, the controller 402determines the presence of a washtub that is in operation. If thepresence of the washtub that is in operation is determined, thecontroller 402 determines whether or not it is necessary to move waterused in the operating washtub. If the movement of water used in theoperating tub is necessary, the controller 402 moves the water from theoperating washtub into a washtub that is not in operation, so as tostore the water in the non-operating washtub.

For example, the controller 402 determines whether or not the firstwashtub 31 and second washtub 32 are in operation. If any one washtub isin the last rinsing stage and the other washtub is not in operation, thecontroller 402 moves water used in the last rinsing stage into thenon-operating washtub, so as to store the water in the non-operatingwashtub. Since the rinse water used in the last rinsing stage isrelatively clean, the rinse water may be recycled later as wash water orrinse water, enabling remarkable reduction in the usage of water in thewashing machine. For example, if the first washtub 31 is in the lastrinsing stage and the second washtub 32 is not in operation, the waterused in the last rinsing stage is moved into and stored in the secondwashtub 32. In this case, if the second washtub 32 is in operation, thewater in the first washtub 31 is discharged to the outside. On thecontrary, if the second washtub 32 is in the last rinsing stage and thefirst washtub 31 is not in operation, the water used in the last rinsingstage is moved into and stored in the first washtub 31. In this case, ifthe first washtub 31 is in operation, the water in the second washtub 32is discharged to the outside.

In addition, the controller 402 determines whether or not the firstwashtub 31 and second washtub 32 are in operation. If any one washtub isin the drying stage and the other washtub is not in operation, thecontroller 402 moves water generated in the drying stage into thenon-operating washtub, so as to store the water in the non-operatingwashtub. Similar to the above-described rinse water, since the watergenerated in the drying stage is relatively clean, it may be recycledlater as wash water or rinse water, enabling remarkable reduction in theusage of water in the washing machine. For example, if the first washtub31 is in the drying stage and the second washtub 32 is not in operation,the water generated in the drying stage is moved into and stored in thesecond washtub 32. In this case, if the second washtub 32 is inoperation, the water in the first washtub 31 is discharged to theoutside. On the contrary, if the second washtub 32 is in the dryingstage and the first washtub 31 is not in operation, the water generatedin the drying stage is moved into and stored in the first washtub 31. Inthis case, if the first washtub 31 is in operation, the water in thesecond washtub 32 is discharged to the outside. The controller 402senses the level of water generated in the drying stage and if thesensed level of water is a preset value or more, moves the watergenerated in the drying stage into the non-operating washtub, so as tostore the water in the non-operating washtub.

After moving the water used in the operating washtub so as to store thewater in the non-operating washtub, the controller 402 determineswhether or not the first washtub 31 and second washtub 32 are inoperation. If there is a washtub to be newly operated, the controller402 moves the water stored in the non-operating washtub into the washtubto be newly operated, allowing the water to be used for a washing orrinsing stage. In this case, the water stored in the non-operatingwashtub is moved into the washtub to be newly operated before the newlyoperated washtub performs any one of washing and rinsing stages orduring the washing or rinsing stage. If the newly operated washtubcorresponds to the previous non-operating washtub and thus, receiveswater already, it may be impossible for the user to open a door of thewashtub. Therefore, it may be necessary to move the stored water into anadditional washtub and then, to return the water into the originalwashtub after completion of, e.g., laundry input and door closingoperations.

The drive unit 404 serves to drive, e.g., the first and second motors 61and 62, first and second washing heaters 71 and 72, first and secondwater supply valves 131 and 132, first and second drying heaters 231 and232, first and second drying fans 241 and 242, first and second coldwater valves 261 and 262, first and second drain pumps 321 and 322,opening/closing valve 502, and pump 503, based on drive control signalsof the controller 402.

Hereinafter, a control method of the washing machine according to theembodiment of the present invention will be described with reference toFIG. 4.

If both washtubs are performing the last rinsing stroke, or if any oneof the washtubs is performing the last rinsing stroke and the otherwashtub is in operation, a conventional control method is implemented.However, if one washtub is performing the last rinsing stroke and theother washtub is not in operation, the control method of the washingmachine according to this embodiment of the present invention isutilized.

FIG. 4 illustrates a control operation of the washing machine accordingto the present embodiment of the present invention.

Referring to FIG. 4, the controller 402 first determines whether or notthe first washtub 31 and second washtub 32 are in operation (600). Inthis case, the controller 402 determines whether the first washtub 31 orthe second washtub 32 is in the last rinsing stage.

Then, the controller 402 determines, based on the determined result ofthe operation mode 600, whether or not any one of the first washtub 31and second washtub 32 is in the last rinsing stage (610).

After determining the presence of the washtub that is in the lastrinsing stage, the controller 402 determines whether or not the firstwashtub 31 is in the last rinsing stage (620). If the determined resultshows that the first washtub 31 is in the last rinsing stage, thecontroller 402 determines whether or not the second washtub 32 is not inoperation (630).

If the second washtub 32 is not in operation, the controller 402 opensthe opening/closing valve 502 of the water moving device 500 and rotatesthe pump 503 forward, moving rinse water of the first washtub 31 used inthe last rinsing stage into the second washtub 32 so as to store therinse water in the second washtub 32 (640) (See FIG. 5). Thereby, thewater may be recycled when the second washtub 32 performs a washingstage or rinsing stage later. In addition, to recycle the water when thefirst washtub 31 performs a following washing stage or rinsing stage,the water may be returned into the first washtub 31 by the water movingdevice 500. This may consequently reduce the usage of water in thewashing machine.

If it is determined, based on the determined result of the operationmode 630, that the second washtub 32 is in operation, the controller 402turns on the first drain pump 321 to discharge the rinse water of thefirst washtub 31 to the outside, in order to prevent the rinse waterfrom having an effect on operation of the second washtub 32 (650).

Meanwhile, if it is determined, based on the determined result of theoperation mode 620, that the first washtub 31 is not in the last rinsingstroke, the controller 420 determines that the second washtub 32 is inthe last rinsing stroke and thus, determines whether or not the firstwashtub 31 is not in operation (660).

If it is determined, based on the determined result of the operationmode 660, that the first washtub 31 is not in operation, the controller402 opens the opening/closing valve 502 of the water moving device 500and rotates the pump 503 rearward, moving the rinse water of the secondwashtub 33 into the first washtub 31 so as to store the rinse water inthe first washtub 31 (670). The water may be recycled when the firstwashtub 31 performs a following washing stage or rinsing stage. Inaddition, to recycle the water when the second washtub 32 performs afollowing washing stage or rinsing stage, the water may be directed intothe second washtub 32 by the water moving device 500. This mayconsequently reduce the usage of water in the washing machine.

Meanwhile, if it is determined, based on the determined result of theoperation mode 660, that the first washtub 31 is in operation, thecontroller 402 turns on the second drain pump 322 to discharge the rinsewater of the second washtub 32 to the outside, to prevent the rinsewater from having an effect on operation of the first washtub 31 (650).

If the first washtub is in the last rinsing stroke as described above oris in the drying stroke, the water used in the last rinsing stroke orgenerated in the drying stroke is moved into and stored in the secondwashtub that is not in operation. In this case, as shown in FIG. 6, thewater stored in the second washtub functions as a so-called balanceweight, acting to reduce the vibration and noise of the entire washingmachine. This is equally applicable to the case where the water used inthe last rinsing stroke and generated in the drying stroke is moved intoand stored in the first washtub that is not in operation. The watermoved into the non-operating washtub is stored until the operatingwashtub is stopped.

Hereinafter, a control method of a washing machine according to anotherembodiment of the present invention will be described with reference toFIG. 7.

If both washtubs are performing the drying stroke, or if any one of thewashtubs is performing the drying stroke and the other washtub is inoperation, a conventional control method is implemented. However, if onewashtub is performing the drying stroke and the other washtub is not inoperation, the control method of the washing machine according to thepresent embodiment is utilized.

Hereinafter, for convenience of description, the following descriptionis based on an application example of the control method in the casewhere the drying devices 201 and 202 are installed to the respectivefirst and second washtubs 31 and 32. However, the control method isequally applicable even to the case where a single drying device isinstalled to the first washtub 31 or the second washtub 32.

FIG. 7 illustrates the control operation of the washing machineaccording to another embodiment of the present invention.

Referring to FIG. 7, the controller 402 first determines whether or notthe first washtub 31 and second washtub 32 are in operation (700). Inthis case, the controller 402 determines whether the first washtub 31 orthe second washtub 32 is in the drying stage.

Then, the controller 402 determines, based on the determined result ofthe operation mode 700, whether or not any one of the first washtub 31and second washtub 32 is in the drying stage (710).

After determining the presence of the washtub that is in the dryingstage, the controller 402 determines whether or not the first washtub 31is in the drying stage (720). If the determined result shows that thefirst washtub 31 is in the drying stage, the controller 402 determineswhether or not the second washtub 32 is not in operation (730).

If the second washtub 32 is not in operation, the controller 402 opensthe opening/closing valve 502 of the water moving device 500 and rotatesthe pump 503 forward, moving condensed water of the first washtub 31(generated in the drying stage) into the second washtub 32 so as tostore the condensed water in the second washtub 32 (740) (See FIG. 8).The water may be recycled when the second washtub 32 performs afollowing washing stage or rinsing stage. In addition, to recycle thewater when the first washtub 31 performs a following washing stage orrinsing stage, the water may be returned into the first washtub 31 bythe water moving device 500. This consequently may reduce the usage ofwater in the washing machine.

Meanwhile, if it is determined, based on the determined result of theoperation mode 730, that the second washtub 32 is in operation, thecontroller 402 turns on the first drain pump 321 to discharge thecondensed water of the first washtub 31 to the outside, in order toprevent the condensed water from having an effect on operation of thesecond washtub 32 (750).

If it is determined, based on the determined result of the operationmode 720, that the first washtub 31 is not in the drying stage, thecontroller 420 determines that the second washtub 32 is in the dryingstage and thus, determines whether or not the first washtub 31 is not inoperation (760).

If it is determined, based on the determined result of the operationmode 760, that the first washtub 31 is not in operation, the controller402 opens the opening/closing valve 502 of the water moving device 500and rotates the pump 503 rearward, moving condensed water of the secondwashtub 32 into the first washtub 31 so as to store the condensed waterin the first washtub 31 (770). The water may be recycled when the firstwashtub 31 performs a following washing stroke or rinsing stroke. Inaddition, to recycle the water when the second washtub 32 performs afollowing washing stroke or rinsing stroke, the water may be returnedinto the second washtub 32 by the water moving device 500. Thisconsequently may reduce the usage of water in the washing machine.

Meanwhile, if it is determined, based on the determined result of theoperation mode 760, that the first washtub 31 is in operation, thecontroller 402 turns on the second drain pump 322 to discharge thecondensed water of the second washtub 32 to the outside, in order toprevent the condensed water from having an effect on operation of thefirst washtub 31 (750).

If the first washtub is in the last rinsing stroke or is in the dryingstroke as described above, the water used in the last rinsing stroke orgenerated in the drying stroke is moved into and stored in the secondwashtub that is not in operation. In this case, as shown in FIG. 9, thewater stored in the second washtub functions as a so-called balanceweight, acting to reduce the vibration and noise of the entire washingmachine. This is equally applicable to the case where the water used inthe last rinsing stroke and generated in the drying stroke is moved intoand stored in the first washtub that is not in operation. The watermoved into the non-operating washtub is stored until the operatingwashtub is stopped.

Also, although the present embodiment illustrates that the water of onewashtub that is in the last rinsing stroke or in the drying stroke ismoved into and stored in the other wash tub that is not in operation,thus acting as a so-called balance weight in the non-operating washtub,the present embodiment is not limited thereto. Simply acquiring theabove-described balance weight via movement of water between bothwashtubs may be possible even when water is newly supplied into onewashtub that is not in operation while the other washtub is inoperation. In this case, the operating washtub may also include awashtub that is performing a washing, rinsing (initial rinsing or middlerinsing), or dehydrating stage except for the last rinsing stage or thedrying stage. In addition, the operating washtub may include a washtubthat is performing any one of a washing stage, rinsing stage,dehydrating stage, and drying stage.

Although the above described embodiments describe the movement of waterfrom the operating washtub into the non-operating washtub, theembodiments of the present invention are not limited thereto, and waterused in one washtub that is in operation may be moved into the otherwashtub that is in operation. For example, if it is necessary to supplywater into the second washtub for a washing or rinsing stage while thefirst washtub is performing the last rinsing stage, the water used inthe first washtub may be moved into the second washtub.

Hereinafter, a method of recycling the water moved into thenon-operating washtub will be described specifically. For convenience ofdescription, the following description is based on the case where twowashtubs are provided, only one of which stores water therein, and boththe washtubs are initially not in operation.

FIG. 10 illustrates an operation of moving water stored in one washtubinto the other washtub to be newly operated in a washing machineaccording to a further embodiment of the present invention.

Referring to FIG. 10, the controller 402 determines whether or not anyone of the first washtub 31 and second washtub 32 stores water (800).

If the presence of the washtub in which water is stored is determined,the controller 402 determines whether or not the first washtub 31 andsecond washtub 32 are in operation (801).

Then, the controller 402 determines, based on the determined result ofthe operation mode 801, whether or not any one of the first washtub 31and second washtub 32 will be newly operated (802). Here, the washtub tobe newly operated is a washtub that will begin a washing stage orrinsing stage.

If the presence of the washtub to be newly operated is determined, thecontroller 402 determines whether or not the washtub to be newlyoperated is the first washtub 31 (803).

If the washtub to be newly operated is the first washtub 31, thecontroller 402 determines whether or not the washtub in which water isstored is the first washtub 31 (804).

If the washtub in which water is stored is the first washtub 31, thecontroller 402 moves the water of the first washtub 31 into the secondwashtub 32 (805). This serves to prevent spillage of water when the useropens the door of the first washtub 31 for washing, or to preventunwanted locking of the door due to the stored water before the userputs laundry into the first washtub because the washtub to be newlyoperated corresponds to the washtub in which water is stored.

After moving the water from the first washtub 31 into the second washtub32, the controller 402 determines whether or not the input of laundry iscompleted (806). If the input of laundry is completed, the controller402 returns the water from the second washtub 32 into the first washtub31 (807). The returned water is recycled for operation of the firstwashtub 31.

On the contrary, if the washtub in which water is stored is the secondwashtub 32, the controller 402 determines whether or not the input oflaundry into the first washtub 31 is completed (806). If the input oflaundry is completed, the controller 402 moves the water from the secondwashtub 32 into the first washtub 31 (807). Accordingly, the storedwater is recycled for operation of the first washtub 31.

If the washtub to be newly operated is the second washtub 32, thecontroller 402 determines whether or not the washtub in which water isstored is the second washtub 32 (808).

If the washtub in which water is stored is the second washtub 32, thecontroller 402 moves the water from the second washtub 32 into the firstwashtub 31 (809). This serves to prevent spillage of water when the useropens the door of the second washtub 32 for washing or to preventunwanted locking of the door due to the stored water before the userputs laundry into the second washtub 32 because the washtub to be newlyoperated corresponds to the washtub in which water is stored.

After moving the water from the second washtub 32 into the first washtub31, the controller 402 determines whether or not the input of laundry iscompleted (810). If the input of laundry is completed, the controller402 returns the water from the first washtub 31 into the second washtub32 (811). The returned water is recycled for operation of the secondwashtub 32.

On the contrary, if the first washtub 31 stores water, the controller402 determines whether or not the input of laundry into the secondwashtub 32 is completed (810). If the input of laundry is completed, thecontroller 402 moves the water from the first washtub 31 into the secondwashtub 32 (811). Accordingly, the stored water is recycled foroperation of the second washtub 32.

As is apparent from the above description, according to an embodiment ofthe present invention, rinse water used in the last rinsing stroke orcondensed water generated in a drying stroke may be moved into andstored in a washtub that is not in operation, rather than being drained.This allows dozens of liters of water to be recycled in a followingwashing stroke or rinsing stroke of the washtub or a washing stroke orrinsing stroke of an additional washtub, resulting in considerablereduction in the usage of water in a washing machine.

Further, according to another embodiment of the present invention, waterused in one washtub that is in operation may be moved into and stored inthe other washtub that is not in operation, or newly supplied water maybe stored in the non-operating washtub. The water stored in thenon-operating washtub may serve as a so-called balance weight of theentire washing machine, acting to reduce the vibration and noise of theentire washing machine.

Although a few embodiments of the present invention have been shown anddescribed, it would be appreciated by those skilled in the art thatchanges may be made in these embodiments without departing from theprinciples and spirit of the invention, the scope of which is defined inthe claims and their equivalents.

1. A control method of a washing machine having a plurality of washtubs,the method comprising: determining whether or not a washtub that is inoperation is present; and if the presence of the washtub that is inoperation is determined, moving water used in the washtub that is inoperation to a washtub that is not in operation.
 2. The control methodaccording to claim 1, wherein the determining of the presence of thewashtub that is in operation includes determining whether or not awashtub that is performing any one of a washing stage, rinsing stage,dehydrating stage, and drying stage is present.
 3. The control methodaccording to claim 2, wherein the determining of the presence of thewashtub that is in operation includes determining whether or not awashtub that is in a last rinsing stage is present.
 4. The controlmethod according to claim 2, wherein the determining of the presence ofthe washtub that is in operation includes determining whether or not awashtub that is in the drying stage is present.
 5. The control methodaccording to claim 4, further comprising: sensing a level of watergenerated in the drying stage of the washtub that is in operation; andmoving the water generated in the drying stage to the washtub that isnot in operation if the sensed level of water is a preset value or more.6. The control method according to claim 1, further comprising: storingthe water moved into the washtub that is not in operation until thewashtub that is in operation is stopped.
 7. The control method accordingto claim 5, further comprising returning the water, moved into thewashtub that is not in operation, when the washtub that is in operationperforms any one of a following washing stroke and rinsing stroke.
 8. Acontrol method of a washing machine having a plurality of washtubs, themethod comprising: determining whether or not a washtub that is inoperation is present; if the presence of the washtub that is inoperation is determined, determining whether or not movement of waterused in the operation is needed; and if movement of the water used inthe operation is needed, moving the water used in the operation to awashtub that is not in operation.
 9. The control method according toclaim 8, wherein the determining whether movement of the water used inthe operation is needed includes determining whether or not the washtubthat is in operation completes a last rinsing stage, and determiningwhether or not a level of water generated in a drying stage reaches apreset value.
 10. A washing machine comprising: a plurality of washtubsincluding a washtub that is in operation and an additional washtub; awater moving device to move water between the plurality of washtubs; anda controller to control the water moving device to move the water usedin a washtub that is in operation to an additional washtub.
 11. Thewashing machine according to claim 10, wherein the controller moves thewater used in the washtub that is in operation, during a last rinsingstage or a drying stage, into the additional washtub, is the additionalwashtub not being in operation.
 12. The washing machine according toclaim 10, wherein the controller moves the water used in the washtubthat is in operation, during any one of a washing stage, rinsing stage,dehydrating stage, and drying stage to the additional washtub, theadditional washtub not being in operation.
 13. The washing machineaccording to claim 10, wherein the water moved into the additionalwashtub is stored under control of the controller until the washtub thatis in operation is stopped.
 14. The washing machine according to claim13, wherein the controller returns the water moved into the additionalwashtub when the washtub that is in operation performs any one of afollowing washing stage and rinsing stage.
 15. The washing machineaccording to claim 10, wherein the water moving device includes at leastone connecting pipe connecting the plurality of washtubs to each other,and an opening/closing valve and pump provided at the connecting pipe.16. The washing machine according to claim 15, wherein the connectingpipe has one end connected to at least one of a drainpipe and condensingduct of the washtub that is in operation, and the other end connected toat least one of a drainpipe and condensing duct of the additionalwashtub.